Breathing aid devices—or ventilation devices—currently used in mechanical ventilation can be divided into two main groups, namely volumetric devices characterized by the supply of a specified volume in each respiratory cycle, and pressure-controlled devices characterized by the provision of a specified pressure in each respiratory cycle.
Volumetric devices have the advantage of guaranteeing a specified breathed volume, but they have major disadvantages. In particular, they expose the patient to risks of barotrauma as they tend to apply pressure which increases at the end of insufflation. Furthermore, the patient risks not being matched to the device in the sense that the respiratory reflexes of the patient can appear at different times from those at which the volumes imposed by the device finish being supplied.
On the contrary, pressure-controlled devices allow better synchronization of the patient with the device and avoid the risk of barotrauma since the maximum pressure supplied is known in advance. On the other hand, the volume supplied to the patient in each cycle and the breathed volume are not guaranteed.